This invention relates to a machine for marking skins or other articles in sheet form by perforation.
Unprocessed or semi-processed skins and generally other articles in sheet form are subjected to marking. in order to impress information regarding the supplier, the production batch, the selection, the thickness, the surface, etc.
To implement this marking, a marking process is known using punches, the end of which forms incisions reproducing arabic numerals in the skin.
A process is also known for marking skins and other objects in sheet form by perforation, in which one or more holes are made in a certain area of the object in positions which enable an optical reader to automatically read the stamped code in the same manner as a bar code. In this specific case the holes are grouped in rows, each row of five holes representing a character. Auxiliary holes are also present, positioned at the corners of the rectangle containing the code, to provide a reference for automatic code reading by the reading device.
To implement the process it is known to use a device comprising within a seat in a base support a plurality of bars each provided with cylindrical punches having a conical end and a central hole for discharging the material. Said punches are applied to each bar in a number and arrangement corresponding to one alphanumeric character in the predetermined code.
This known device, which has the advantage of instantaneous marking, presents on the other hand certain drawbacks, and in particular:
laborious bar substitution when changing the number to be coded,
poor skin consistency around the hole because of stretching due to the conical profile of the punch.
Marking devices are also known with a punch movable along a line or in two perpendicular directions under the control of a computer.
These devices, which enable the coded number to be easily changed by simply operating the computer keyboard, have the drawback of being slow in operation because the holes have to be made one at a time.
DE-U-9419403 relates to an arrangement for forming strip-shaped material with at least one adjustable tool carrying module which can be actuated by means of a drive. Two modules are provided, each carrying at least two independently usable tools and/or at least one processing unit, which modules can be adjusted in the longitudinal and/or transverse direction relative to the feed direction of the material to be processed.
An object of the invention is to provide a machine for marking skins by perforation in which the coded number to be marked can be quickly and easily changed, and which is very fast in operation.
This object and further ones are attained according to the invention through a machine for marking skins or other articles in sheet form by perforation, by comprising:
a support structure for m rows each formed from n vertical punches, m and n being whole numbers with mxe2x89xa7 and nxe2x89xa72, the upper ends of said punches being inserted into holes of a corresponding plate elastically supported on said support structure, each lower end of said vertical punches of each row interacting with a corresponding wedge element of a plurality of n.m. wedge elements, each wedge element being operable by an axial movement of a corresponding operating bar to position said punches between two end positions in which the punches remain fixed, in one of which a cutting edge of punches is substantially at the level of an upper surface of said plate and in the other of which said cutting edge of the punches lies inside said hole, the distance between the two end positions of said cutting edge corresponding with the thickness of said operating bars for said wedges,
moving means for said bars,
a counterplate facing said plate and movable vertically towards and away from said plate to cause this latter to descend together with a skin retained between them towards said punches and obtain perforation by only those punches which have their cutting edge at the level of the upper surface of the plate and which have been positioned in an arrangement corresponding to an alphanumeric character in accordance with a predetermined code.